I see this is an older thread, but no one answered. I am running a new 2014 Mac Book Pro and using dual MR816CSX interfaces. The Thunderbolt-to-firewire adapter works well. Just need a firewire 800 to 400 cable. I had no problems at all running this. Now, I have since added the Thunderbolt Display, and it has a built in FW800 port. I now use this, but have noticed that when my Mac idles (maybe when it wakes up after sleep mode) the MR816 has a huge input latency. I have to go into the Device setup on the MR and click on the buffer size and it goes back to functioning normally. I have not spent the time to figure out exactly what is happening, yet.